Not Going over 45 MPH!

[GoodCubanito]

Hi guys. 2016 242 LS here... boat used to get up to 50-51 MPH but now it tops at 45 MPH. Hull is clean, maintenance was done properly, dealer says nothing wrong showing up on their tests. Only change I made was to install the Thrust vectors. Engines sound as usual, any suggestions on what to look at next?

Thanks in advance and happy Labor Day!

 

[Julian]

Have you checked the intake tunnel for missing silicon?
Have you loaded the boat with lots of stuff (weight)?
Have you checked the impeller gap tolerance?

All of the above could be your issue...

 

[haknslash]

Any cavitation? I’d look over all the basic thrust related parts (impeller, gap, intake etc).

When is the last time you changed spark plugs? I know it sounds funny but these things are picky about running great with less than optimal spark plugs.

 

[GoodCubanito]

Have you checked the intake tunnel for missing silicon?
Have you loaded the boat with lots of stuff (weight)?
Have you checked the impeller gap tolerance?

All of the above could be your issue...

Thank you Julian for the points... however, I have no clues how to check for the stuff you mentioned... any educational points, please? Thanks again.

 

[Julian]

Thank you Julian for the points... however, I have no clues how to check for the stuff you mentioned... any educational points, please? Thanks again.

To check for missing silicone in the intake tunnel, you need to lay on your back and get under the boat. You are looking for gaps or holes where there used to be silicon.


Weight - do you have a TON of stuff in your boat now? If so, added weight will slow you down.
Impeller gap tolerance.....see the chart below, you would need a gap "feeler" to measure this gap (.6mm MAX gap between the impeller and the housing - ideal is between .35 to .45mm):


I got this from an older (2005) service manual - if anyone has a newer one for this model year boat - feel free to post it - but this should be close if not identical.

 

[GoodCubanito]

To check for missing silicone in the intake tunnel, you need to lay on your back and get under the boat. You are looking for gaps or holes where there used to be silicon.
View attachment 162648

Weight - do you have a TON of stuff in your boat now? If so, added weight will slow you down.
Impeller gap tolerance.....see the chart below, you would need a gap "feeler" to measure this gap (.6mm MAX gap between the impeller and the housing - ideal is between .35 to .45mm):
View attachment 162649

I got this from an older (2005) service manual - if anyone has a newer one for this model year boat - feel free to post it - but this should be close if not identical.

WoW... awesome info. I have the service manual and will check it out... thank you very much! Great start to this troubleshooting step.

 

[Cobra Jet Steering LLC]

You know the warmer the water and the weather the slower the boat will go, you could also have an exhaust leak in the engine compartment just one hose clamp falling off a hose in the exhaust system can fill the compartment with carbon monoxide and rob your top speed. As can a dirty air filter or Slightly over filled oil or a worn pump ring or stale fuel.